Please help identifying a light leak

[Martin Patek-Strutsky]

Recently I became aware of a foggy stripe about 20 mm wide on two out of twenty 4x5 slides processed in one batch.

The stripe is located on the opposite side of where the dark slide is removed during exposure. So the usual weak spot of film holders can not be the reason. The camera itself is light tight, too.

Has anyone experienced leaks in the mentioned area? Is this most probably a lab issue or do I need to take the hassle of testing all my film holders?

Regards Martin

P.S. I use only Fidelity Elite holders in very good condition

[Jim Rice]

Might it be an internal reflection? Indications would be a lens with excess coverage, and a strong light source in or near the photograph.

[Kirk Gittings]

The possibilities are enormous. It is obviously not the holders as it occurs with film from all the holders. Start by shooting some polaroid in bright daylight and throwing a dark cloth over the bellows, the back etc. and narrow it down. If it is the bellows, put a flashlight inside them in a dark room. Move it around looking for light leaks from all angles with the bellows stretched and extreme rises etc.

[Doug Pollock]

The presence of a "stripe" suggests that the whole film holder is being held up, slightly away from contact with the camera. The fact that the problem is intermittent suggests a problem with insertion of the holder. Maybe when a film holder is pushed in too far it rides up on a ridge designed to retain the end of the film holder.

[Jan Nieuwenhuysen]

I would suspect the film holders first:

- Dark slide not being pushed down far enough (or pulled out a little e.g. when you took the holder out of the bag or case). The small hooks that lock the dark slides in the Elite holder can become very loose after some time.

- Leaking hinge tape? Less probable I think.

[Brian Ellis]

Light leaks from bellows problems don't, in my experience at least, show up as a single stripe in the same place every time. When I've had a hole in the bellows the problem has appeared either as random streaks or almost as a double image. If the edge of the stripe is sharp and reasonbly well defined, I'd suspect that the dark slide somehow was pulled up a little at some point in the process of making the photographs.

With respect to the "leaking tape" suggestion that someone mentioned, the tape doesn't prevent light from getting into the holder. The light trap at the bottom of the holder performs that function. The tape serves only as a hinge to allow film to be inserted in and removed from the holder. Since the tape doesn't block any light in the first place, it couldn't be leaking light and causing your problem.

[Ole Tjugen]

I had a leaking camera back for a while. A strip of velvet was missing from one long side of the back. This gave light leaks about 2cm in from the edge of the film on some exposures. All holders were equally affected, and it only happened occasionally. In the same day I could do exposures at 1/400s and 30s, and one would show a leak and the other not.

If the leak is a little distance in from the bottom of the holder and all holders are affected, check the camera back. Bellows leaks tend to be either more diffuse or sharper, depending on lighting conditions.